[PATCH v3 17/18] arm64: arch_timer: Allow erratum matching with ACPI OEM information

From: Marc Zyngier
Date: Tue Apr 04 2017 - 13:19:16 EST


Just as we're able to identify a broken platform using some DT
information, let's enable a way to spot the offenders with ACPI.

The difference is that we can only match on some OEM info instead
of implementation-specific properties. So in order to avoid the
insane multiplication of errata structures, we allow an array
of OEM descriptions to be attached to an erratum structure.

Tested-by: dann frazier <dann.frazier@xxxxxxxxxxxxx>
Tested-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Reviewed-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
arch/arm64/include/asm/arch_timer.h | 1 +
drivers/clocksource/arm_arch_timer.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 6bd1a9a1573a..74d08e44a651 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -41,6 +41,7 @@ extern struct static_key_false arch_timer_read_ool_enabled;
enum arch_timer_erratum_match_type {
ate_match_dt,
ate_match_local_cap_id,
+ ate_match_acpi_oem_info,
};

struct clock_event_device;
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 8459d19a84f5..887f6d00a71d 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -190,6 +190,12 @@ static struct cyclecounter cyclecounter __ro_after_init = {
.mask = CLOCKSOURCE_MASK(56),
};

+struct ate_acpi_oem_info {
+ char oem_id[ACPI_OEM_ID_SIZE + 1];
+ char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
+ u32 oem_revision;
+};
+
#ifdef CONFIG_FSL_ERRATUM_A008585
/*
* The number of retries is an arbitrary value well beyond the highest number
@@ -371,6 +377,28 @@ bool arch_timer_check_local_cap_erratum(const struct arch_timer_erratum_workarou
return this_cpu_has_cap((uintptr_t)wa->id);
}

+
+static
+bool arch_timer_check_acpi_oem_erratum(const struct arch_timer_erratum_workaround *wa,
+ const void *arg)
+{
+ static const struct ate_acpi_oem_info empty_oem_info = {};
+ const struct ate_acpi_oem_info *info = wa->id;
+ const struct acpi_table_header *table = arg;
+
+ /* Iterate over the ACPI OEM info array, looking for a match */
+ while (memcmp(info, &empty_oem_info, sizeof(*info))) {
+ if (!memcmp(info->oem_id, table->oem_id, ACPI_OEM_ID_SIZE) &&
+ !memcmp(info->oem_table_id, table->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
+ info->oem_revision == table->oem_revision)
+ return true;
+
+ info++;
+ }
+
+ return false;
+}
+
static const struct arch_timer_erratum_workaround *
arch_timer_iterate_errata(enum arch_timer_erratum_match_type type,
ate_match_fn_t match_fn,
@@ -431,6 +459,9 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
match_fn = arch_timer_check_local_cap_erratum;
local = true;
break;
+ case ate_match_acpi_oem_info:
+ match_fn = arch_timer_check_acpi_oem_erratum;
+ break;
default:
WARN_ON(1);
return;
@@ -1277,6 +1308,9 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
/* Always-on capability */
arch_timer_c3stop = !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);

+ /* Check for globally applicable workarounds */
+ arch_timer_check_ool_workaround(ate_match_acpi_oem_info, table);
+
arch_timer_init();
return 0;
}
--
2.11.0